AkousaFrequency Analysis
Perform letter and bigram frequency analysis for cryptanalysis.
About Frequency Analysis
Frequency Analysis calculates the precise occurrence rate of individual letters, bigrams (letter pairs), and trigrams in any text sample and visualizes the distribution as interactive bar charts, enabling the classical cryptanalytic technique first described by Al-Kindi in the 9th century. English text has a well-documented frequency distribution where 'e' (12.7%), 't' (9.1%), and 'a' (8.2%) dominate, and substitution cipher plaintexts mirror this distribution despite the substitutions. By overlaying your ciphertext's frequency distribution against known-language tables, patterns emerge that can break monoalphabetic and simple polyalphabetic ciphers.
How to Use
Paste your plaintext, ciphertext, or sample text into the input field — the frequency analysis updates in real time as you type. Switch between letter, bigram, and trigram views using the tabs to examine different levels of pattern granularity. The bar chart uses color intensity to highlight the most frequent symbols, and hovering any bar shows exact count and percentage. Compare your ciphertext distribution against the built-in English reference frequencies to identify likely substitution mappings.
Common Use Cases
- Cryptanalysts and CTF players breaking monoalphabetic substitution ciphers by mapping the highest-frequency ciphertext symbols to their expected plaintext equivalents based on English letter distributions
- Linguistics researchers comparing letter frequency profiles between language samples to identify the source language of an unknown document or measure stylometric differences between authors
- Cryptography educators demonstrating why simple substitution ciphers are insecure by showing students live frequency analysis results that immediately reveal the plaintext language and likely mappings
- Security researchers evaluating whether a cipher output passes basic frequency analysis as a first-pass test for randomness and proper diffusion before deeper statistical testing
- Puzzle designers and ARG creators analyzing frequency patterns in their custom cipher designs to verify the challenge provides an appropriate difficulty level without trivially obvious frequency signatures